407P Pembrolizumab Expanded Access Program (EAP) in Taiwan for patients with progressive advanced melanoma after prior ipilimumab treatment

Abstract

Background: Pembrolizumab, a programmed death 1 (PD-1) inhibitor, has been approved for treatment of advanced melanoma based on a significant survival improvement in patients who are refractory to other treatments and as the first line treatment. We evaluated the clinical activity of pembrolizumab in melanoma patients in Taiwan under the expanded access program. Methods: From December 2014 through June 2016, we enrolled patients with progressive unresectable stage III/IV melanoma, who have previously received ipilimumab and BRAF/MEK inhibitors if BRAF mutation. Pembrolizumab was given at 2 mg/kg every three weeks continuously until development of intolerable side effects or progression of disease per study protocol's designation. Results: Data were collected from23 advanced melanoma patients (15 cutaneous, 6 mucosal and 2 of unknown primary). 20 patients (61%) received at least 2 lines of treatment previously, and 6 patients (26%) with stable brain metastases were enrolled. Median overall survival (OS) was 6.7 months (CI 95% 4.6-8.8). 12-month OS was 38% and 15-month OS was 30%. Among 20 evaluable patients, 4 patients achieved a partial response, and 8 patients achieved a stable disease, with an overall response rate of 20.0% (CI 95% 0-39%) and clinical benefit rate of 60% (CI 95% 36-84%). The most common drug-related adverse events of any grade were rash (35%), pruritus (30%), and fatigue (30%). Two deaths were considered treatment-related; one cytokine storm and one ventricular tachycardia. Conclusions: Pembrolizumab's activity in melanoma as a second line immune checkpoint inhibitor (after prior exposure of ipilimumab) was confirmed in Taiwan. Durable response, even in the previously heavily-treated patients, has been observed.